Efficient Charge Transfer Mechanism in Polyfluorene/ZnO Nanocomposite Thin Films

Bandar Ali Al-Asbahi,Mohammad Hafizuddin Haji Jumali,Rashad Al-Gaashani

doi:10.1155/2014/608572

Bandar Ali Al-Asbahi, Mohammad Hafizuddin Haji Jumali + Show 1 more

Open Access

https://doi.org/10.1155/2014/608572

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Abstract

The optical properties and charge transfer mechanism of poly (9,9′-di-n-octylfluorenyl-2.7-diyl) (PFO)/ZnO thin films have been investigated. The ZnO nanorods (NRs) were prepared via a microwave technique. The solution blending method was used to prepare the PFO/ZnO nanocomposites. X-ray diffraction (XRD) and field emission scanning electron microscope (FE-SEM) were used to determine the structural properties, while UV-Vis and photoluminescence (PL) were employed to investigate the optical properties of the films. XRD patterns confirmed that there was no variation in the structure of both PFO and ZnO NRs due to the blending process. FE-SEM micrographs displayed that ZnO NRs were well coated by PFO in all nanocomposite films. The absorption spectra of the nanocomposite thin films exhibited a red-shift indicating the increment in conjugation length of the PFO/ZnO nanocomposite. Significant quenching in the emission intensity of PFO was observed in fluorescence spectra of the nanocomposite films. This quenching was attributed to efficient charge transfer in the PFO/ZnO nanocomposites, which was further supported by the shorter PL lifetime of PFO/ZnO than that of the PFO thin film. The continuous decline in PL intensity of these nanocomposites is attributed to homogenous dynamic quenching between PFO and ZnO NRs.

Highlights

The growing interest in polymer based photoelectric devices, in particular conjugated polymer, can be attributed to several factors such as environmentally friendly, adjustable band gaps, high optical absorption coefficient, and low-cost fabrication
The X-ray diffractograms for nanocomposite thin films consist of broad PFO peaks with several narrow peaks representing ZnO NRs
This work reports on the study of charge transfer mechanism in PFO/ZnO nanocomposite thin films

Summary

Introduction

The growing interest in polymer based photoelectric devices, in particular conjugated polymer, can be attributed to several factors such as environmentally friendly, adjustable band gaps, high optical absorption coefficient, and low-cost fabrication. As one of the most widely investigated materials, ZnO is commonly used as electron acceptor in polymer/inorganic nanocomposites [17,18,19,20] This metal oxide exhibits greater tendency to stabilize in wurtzite hexagonal form with conduction band, valence band, and energy gap of −4.2, −7.6, and 3.4 eV, respectively [18]. Most of the earlier works on polymer/ZnO nanocomposites demonstrated the photoluminescence (PL) quenching which was conveniently claimed due to efficient charge transfer effect [17,18,19]. The current work is calculated fluorescence lifetime, and other important parameters, namely, the quenching rate constant [22] and photo-induced electron transfer rate [23], which are used together as supplementary evidence to indicate tendencies of determined systems. The quenching type and quenching efficiency were determined in order to have more comprehensive information on the suitability of this nanocomposite as an active layer in the photoelectric devices

Experimental Details

Results and Discussion

Conclusion